A conventional system for identifying and tracking aircraft and ground vehicles is the Air Traffic Control Radar Beacon System (ATCRBS), which comprises three components: 1) ground interrogation equipment, 2) transponder equipment located on aircraft and ground vehicles, and 3) surface movement radar (SMR). The ground interrogation equipment comprises two types of radar systems: 1) the primary surveillance radar (PSR), and 2) the secondary surveillance radar (SSR). Many conventional PSR and SSR radar antennas in use today are of the mechanically-operated, dish type.
PSR operates using traditional radar principles, transmitting radio pulses and listening for and timing the reflections from the skin or other metal components of aircraft. PSR provides air traffic control (ATC) with range and bearing of aircraft. PSR has no capability to specifically indentify aircraft or ground vehicles.
SSR, on the other hand, provides ATC with unique information about the aircraft type and altitude. This information is provided via the squitter and transmits information that the aircraft has regarding its own position. SSR relies exclusively on transponders located on aircraft for identification and location information. The equipment installed in an aircraft is the transponder itself, usually mounted in the instrument panel or avionics rack, and a small UHF (ultra-high frequency) antenna, mounted on the bottom of the aircraft fuselage. Many commercial aircraft have an antenna on top of the fuselage, and either or both antennas can be selected by the flight crew.
SMR provides surveillance of aircraft and vehicle movement on airport runways and taxiways. SMR is also, in many instances, a mechanically operated, dish type antenna system. Even though PSR and SSR can be integrated, SMR functions as a separate system. There are separate displays for the SMR data on an ATC console. SMR does not have capability to identify aircraft or ground vehicles, and SMR relies on transponders on the aircraft or vehicle for identification.
Accordingly, in conventional tracking systems, three radar systems are needed: the primary surveillance radar (PSR), the secondary surveillance radar (SSR), and the surface movement radar (SMR). Hardware and software for these is unique to each system and is not interchangeable. Therefore, initial cost, upgrades, and maintenance typically require 2 to 3 times the resources that a single system requires. Moreover, conventional PSR, SSR, and SMR systems use mechanical dish radars. These huge mechanical dish radars are expensive to install, have numerous failure modes, and require high maintenance.
As such, there currently exists a need to improve radar tracking and identifying systems for aircraft and ground vehicles in airspace and airport terminal areas.